Writer’s Blog

Which and that—what’s the difference?

Should I use which or that?

People often use them interchangeably, but the word you choose gives a subtly different meaning. Get it right to show your clear thinking and writing abilities.

A simple example

The car, which my parents bought me, is silver.

The car that my parents bought me is silver.

In the first example the fact that my parents bought it is incidental.

Look at the punctuation—with which you need commas. They separate the phrase “which my parents bought me”. You can think of them as brackets. The fact my parents bought the car is not important. The car is silver, and happens to have been bought for me by my parents.

On the other hand, in example number two the detail “that my parents bought me” is essential because it defines the car. There’s a possibility I may own more than one car, and the other(s) were not bought by my parents.

Don’t use a comma with that, because it forms part of the noun-phrase “the car that my parents bought me”.

Sometimes we can leave out the word that, so we get:

The car my parents bought me is silver.

A business example

This is from real proposal I recently helped with:

We’ll focus on supporting communities within areas which are the most deprived.

Here we can’t put “which are the most deprived” in brackets. This element is essential to the “areas” we’re talking about, so we need to use that.

We’ll promote activities through our newsletter, which reaches over 50,000 people, and through social media.

Here the fact the newsletter reaches many people is useful information, but not defining, so which is correct.

Grammar terms

Because that defines what we’re talking about, we call this part of the phrase (“that my parents bought me”) a defining relative clause.